Mr Vaz, 59, quit as chairman of the Home Affairs Select committee after the Sunday Mirror claimed he paid to have sex with two male escorts at a north London flat.

In a secret recording, the father-of-two allegedly indicated to one of the men he would pay for cocaine, but would not use it himself, according to the newspaper.

The recording also included a discussion about the legal party drug poppers.

Mr Vaz said he will cooperate with police in the probe.

Mr Vaz said he will cooperate with police (Picture: Getty Images)

In a statement, Mr Vaz’s solicitor, Mark Stephens, said: ‘Our client welcomes a full investigation as a means of establishing the true facts and is confident the police will pursue all lines of inquiry.

‘He will cooperate with the investigation in any way he can. He does not intend to comment on this matter any further.’

A Scotland Yard spokesman said: ‘Following that assessment, which included obtaining early investigative advice from the Crown Prosecution Service, the Metropolitan Police is now investigating offences under the Misuse of Drugs Act 1971.

‘The investigation started on Thursday November 10.’

In the wake of the revelations, Tory MP Andrew Bridgen, said he would write to Scotland Yard calling for Mr Vaz to be investigated for misconduct in a public office and conspiracy to supply controlled substances.